Eliminate callhome-status.yang

callhome-status.yang is an extension of the model packaged in the same directory, providing just a simple augmentation to the operational datastore.

As such, its naming violates naming, as it does not start with odl-prefix, leading to potential conflicts with outside world. It also needlessly complicates things.

Integrate it into odl-netconf-callhome-server and adjust users.